HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 288/2/G268    most recent 00330.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Somara, S. Articles by Bitar, K. N. Search for Related Content PubMed PubMed Citation Articles by Somara, S. Articles by Bitar, K. N.

NEUROREGULATION AND MOTILITY

Agonist-induced association of tropomyosin with protein kinase C in colonic smooth muscle

Department of Pediatrics, University of Michigan Medical, enter, Ann Arbor, Michigan

Submitted 27 July 2004 ; accepted in final form 7 October 2004

Smooth muscle contraction regulated by myosin light chain phosphorylation is also regulated at the thin-filament level. Tropomyosin, a thin-filament regulatory protein, regulates contraction by modulating actin-myosin interactions. Present investigation shows that acetylcholine induces PKC-mediated and calcium-dependent phosphorylation of tropomyosin in colonic smooth muscle cells. Our data also shows that acetylcholine induces a significant and sustained increase in PKC-mediated association of tropomyosin with PKC in the particulate fraction of colonic smooth muscle cells. Immunoblotting studies revealed that in colonic smooth muscle cells, there is no significant change in the amount of tropomyosin or actin in particulate fraction in response to acetylcholine, indicating that the increased association of tropomyosin with PKC in the particulate fraction may be due to acetylcholine-induced translocation of PKC to the particulate fraction. To investigate whether the association of PKC with tropomyosin was due to a direct interaction, we performed in vitro direct binding assay. Tropomyosin cDNA amplified from colonic smooth muscle mRNA was expressed as GST-tropomyosin fusion protein. In vitro binding experiments using GST-tropomyosin and recombinant PKC indicated direct interaction of tropomyosin with PKC. PKC-mediated phosphorylation of tropomyosin and direct interaction of PKC with tropomyosin suggest that tropomyosin could be a substrate for PKC. Phosphorylation of tropomyosin may aid in holding the slided tropomyosin away from myosin binding sites on actin, resulting in actomyosin interaction and sustained contraction.

acetylcholine; fusion proteins

This article has been cited by other articles:

				S. Somara and K. N. Bitar Direct association of calponin with specific domains of PKC-{alpha} Am J Physiol Gastrointest Liver Physiol, December 1, 2008; 295(6): G1246 - G1254. [Abstract] [Full Text] [PDF]

				P. Gunning, G. O'neill, and E. Hardeman Tropomyosin-Based Regulation of the Actin Cytoskeleton in Time and Space Physiol Rev, January 1, 2008; 88(1): 1 - 35. [Abstract] [Full Text] [PDF]

				F. Houle, A. Poirier, J. Dumaresq, and J. Huot DAP kinase mediates the phosphorylation of tropomyosin-1 downstream of the ERK pathway, which regulates the formation of stress fibers in response to oxidative stress J. Cell Sci., October 15, 2007; 120(20): 3666 - 3677. [Abstract] [Full Text] [PDF]

				D. P. Poole and J. B. Furness PKC {delta}-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle Am J Physiol Gastrointest Liver Physiol, March 1, 2007; 292(3): G887 - G898. [Abstract] [Full Text] [PDF]

				S. Somara and K. N. Bitar Phosphorylated HSP27 modulates the association of phosphorylated caldesmon with tropomyosin in colonic smooth muscle Am J Physiol Gastrointest Liver Physiol, October 1, 2006; 291(4): G630 - G639. [Abstract] [Full Text] [PDF]

				H. Pang and K. N. Bitar Direct association of RhoA with specific domains of PKC-{alpha} Am J Physiol Cell Physiol, October 1, 2005; 289(4): C982 - C993. [Abstract] [Full Text] [PDF]